So just one quick question on the mixing of stainless and aluminum. When I last replaced my worn-out rudder cables, I used stainless cable, but connected it to my rudder using little aluminum sleeves that you loop the cable through, then crimp to hold the cable tight. Is this kind of connection likely to fail prematurely? (I actually did have one fail already, but I assumed that was due to using a little too much force on my crimper). What would be a better way of attaching the stainless cable? Evan Woodinville, WA *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
From: "Evan Dallas" <Evan_Dallas_at_notes.ntrs.com> > So just one quick question on the mixing of stainless and aluminum. When I > last replaced my worn-out rudder cables, I used stainless cable, but > connected it to my rudder using little aluminum sleeves that you loop the > cable through, then crimp to hold the cable tight. Is this kind of > connection likely to fail prematurely? (I actually did have one fail > already, but I assumed that was due to using a little too much force on my > crimper). Mixing two different metals will accelerate the corrosion; something to do with electrochemistry that I only vaguely understand. Stick a piece of zinc and a piece of copper into a lemon and you get a battery, with two pieces of zinc or two pieces of copper you don't. Putting a piece of zinc on a steel boat hull minimizes corrosion of the steel by sacrificing the zinc. Ditto pipelines and stuff. Since the zinc is not used for strength, no problem. Zinc plating steel does the same. In Britain years ago, they made a bunch of bridges out of aluminum (or aluminium over there) but used steel bolts. The bolted joints corroded dangerously and the bridges had to be replaced prematurely - something of a scandal at the time. For this reason, using aluminum crimps on stainless cables has the potential to corrode faster than if you used stainless crimps (or zinc cables). Since I haven't spent much time with my ruddered kayak in salt water, I can't tell what happens in the real world. It is likely that if you over-squished the crimps they could crack and eventually fail. If they corrode, there should be a white powder on the aluminum and the surface should be rough. > What would be a better way of attaching the stainless cable? Do they use stainless crimps on most kayaks? That would make sense. I don't remember what was originally on my Solstice. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Corrosion from dissimilar metals is a real problem around water, particularly salt water. It is not a good idea to have mixed metals in this kind of environment. If I remember correctly from my sailing and aircraft maintenance days, the metal that is lower on the periodic chart will be sacrificed in this kind of situation. In the case you present, weakening of the aluminum will be accelerated. I would recommend that you rework your rudder cables with all stainless parts, particularly if you're around salt water and don't rinse the equipment with fresh water after use. There are stainless cable clamps that might be a better choice than the aluminum sleeves. I don't know if stainless sleeves are readily available offhand. I once made a set of clad aluminum hinges for a locker on my sailboat and assembled them with stainless hardware because I was too cheap to buy stainless hinges. I had to replace the aluminum parts within a year. Caveat - the boat was in salt water year round. YMMV, Dave G. Poquoson, Va. At 01:36 PM 11/7/2002 -0800, Evan Dallas wrote: >So just one quick question on the mixing of stainless and aluminum. When I >last replaced my worn-out rudder cables, I used stainless cable, but >connected it to my rudder using little aluminum sleeves that you loop the >cable through, then crimp to hold the cable tight. Is this kind of >connection likely to fail prematurely? (I actually did have one fail >already, but I assumed that was due to using a little too much force on my >crimper). What would be a better way of attaching the stainless cable? > >Evan >Woodinville, WA *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
----- Original Message ----- From: Evan Dallas So just one quick question on the mixing of stainless and aluminum. When I last replaced my worn-out rudder cables, I used stainless cable, but connected it to my rudder using little aluminum sleeves that you loop the cable through, then crimp to hold the cable tight. Is this kind of connection likely to fail prematurely? Evan, As water chemist, I can assure you that any time you put dissimilar metals in contact with a conductive medium, you will have corrosion ocurring. The salt water is very conductive by the way. The only thing you can do to prevent this is to not let 2 or more dissimilar metals be in close contact with each in the water. Additionally, high levels of chloride attack stainless steel. This results in intergrannular stress corrosion. So if you are stressing the metal (crimping?), you will actually increase the corrosion rates. Hope this helps, Steve Holtzman *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Take a look at: http://www.metal-mart.com/Guides/Galvanic.htm To minimize corrosion you want metals that are close together on this chart. As you can see Aluminum and Stainless are very far apart. The aluminum will corrode quite quickly. You can get the squeeze fittings in stainless and other materials: http://bosunsupplies.com/NicopressSwage.cfm On Thursday, November 7, 2002, at 04:36 PM, Evan Dallas wrote: > So just one quick question on the mixing of stainless and aluminum. > When I > last replaced my worn-out rudder cables, I used stainless cable, but > connected it to my rudder using little aluminum sleeves that you loop > the > cable through, then crimp to hold the cable tight. Is this kind of > connection likely to fail prematurely? (I actually did have one fail > already, but I assumed that was due to using a little too much force > on my > crimper). What would be a better way of attaching the stainless cable? > Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
The oval sleeves we use for rudder cable at Alder Creek are copper. This is not too bad to mix with stainless steel and is the marine industry standard for making eyes in SS wire. They come either copper colored or sometimes with a shinny coating. Maybe the shinny coated ones are what you are refering to as aluminium. Mixing aluminium and SS is a definite no-no. steve Alder Creek Kayak & Canoe N 45º 39' 47" 250 NE Tomahawk Isle Dr. W 122º 36' 16" Portland, OR 97217 Web: www.aldercreek.com Phone: 503.285.0464 Email: aldercreek_at_qwest.net *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
We (and anyone using Yakima/NW Designs foot pedals) has been screwing a stainless steel screw through threads into aluminum for well over 20 years. Maybe if it was constantly under salt water there would be a problem. I don’ t recall ever seeing any significant corrosion because of it. What corrosion that does occur in normal salt water use seems to weld the two materials together more tightly. In the early 1980’s NW Kayaks used to put a screw through 3 or 4 layers of 1/8” aluminum when mounting one type of footbrakes. Those ¼ inch screws could be a real bugger to remove if they were old. Sometime I’ve had to resort to a hacksaw to make a much deeper slot in the screw so I could use an impact wrench to bust those screws loose. We were replacing them with our system because of a broken plastic part that would get brittle with age (and was no longer available in that size) not because of anything to do with incompatibility between the metals or corrosion on them. I have seen some pretty corroded rudder fittings and parts on older kayaks used in salt water a lot. Most rudders use stainless steel screws into aluminum but that was not the areas I saw corrosion problems. They seemed more likely on the cable ends or places where aluminum fit in tightly against other aluminum. Stainless screws must be of a hard enough grade to allow cutting of the threads into them. They can get a little surface discoloration on them if kept constantly wet. The only place I usually see this surface discoloration is on the spare wing-nut we string onto the nylon hatch attachment cord. I assume the cord holds the salt and moisture in place a lot longer. This staining is not really corrosion because it doesn’t “eat” into the material but just stays on the surface in a thin layer. My understanding is that’s because the new oxide is slightly smaller than the material it was formed from. Rust (iron oxide) expands to bigger than the material it was formed from so it buckles up and flakes exposing new steel underneath to be corroded further. I thought crevice corrosion in stainless steel occurred because of electrolysis between the materials (even though they were the same material) touching each other. I’m not very sure of that though so please don’t quote me on it. I have noticed that the stainless buttons on two piece graphite paddles are much more likely to stain than the ones on fiberglass paddles. I have guessed that this is due to the carbons greater electrical conductivity but I’d be happy to hear other possibilities from those more informed on this subject. We quit using any nuts on the bow and stern U-bolt placements because some of the earliest ones we did that were used in salt water a lot were staining the boat a little below the U-bolts probably due to crevice corrosion. Matt Broze http://www.marinerkayaks.com <http://www.marinerkayaks.com/> *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
The crevice corrosion is actually a result of differences in the concentration of oxygen in the water. The water in the crevice becomes deficient in oxygen compared to the water on the outside of the crevice. This sets up an electron flow and as a result there is corrosion. By definition, electrolysis is always dissimilar metals. Can't comment on the rest because I deal with the chemistry of water--I'm not a metallurgist. Steve Holtzman Matt said, I thought crevice corrosion in stainless steel occurred because of electrolysis between the materials (even though they were the same material) touching each other. I'm not very sure of that though so please don't quote me on it. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:31 PDT